Method and system for servicing wind turbine rotor

ABSTRACT

A system for enabling servicing of a rotor of a wind turbine has a rotor blade sling with at least one strap configured to be placed over the top of a rotor blade in a ten o&#39;clock position or a two o&#39;clock position. One or more rigid bars extend from the hub and out away from the hub, and the one or more rigid bars are coupled to the at least one strap. One or more support straps are coupled to the at least one strap, and the one or more support straps are configured to couple and support a rotor blade in a six o&#39;clock position.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of application Ser. No. 14/257,538filed on Apr. 21, 2014.

FIELD OF THE INVENTION

The present subject matter relates generally to wind turbines and, moreparticularly, to an improved method and system for enabling servicing ofthe rotor of a wind turbine.

BACKGROUND OF THE INVENTION

Wind power is considered one of the cleanest, most environmentallyfriendly energy sources presently available, and wind turbines havegained increased attention in this regard. A modern wind turbinetypically includes a tower, generator, gearbox, nacelle, and one or morerotor blades. The rotor blades capture kinetic energy of the wind usingknown foil principles. The rotor blades transmit the kinetic energy inthe form of rotational energy so as to turn a shaft coupling the rotorblades to a gearbox, or if a gearbox is not used, directly to thegenerator. The generator then converts the mechanical energy toelectrical energy. A power converter typically regulates the flow ofelectrical power between the generator and a grid.

Typically, to initially install a rotor blade onto the wind turbine huband/or to remove or lower one of the existing rotor blades from the hub,a significantly large crane must be transported to the wind turbine sitein order to provide a means for raising and/or lowering the rotor bladerelative to the hub. Unfortunately, it is often extremely expensive toboth transport the crane to the wind turbine site and operate the cranefor the amount of time necessary to install and/or remove/lower therotor blade(s). As a result, the costs of employing such large cranescurrently accounts for a significant portion of the overall costsassociated with initial wind turbine installations and rotor maintenanceor service operations.

Accordingly, an improved method and related system for lowering windturbine rotor blades to enable rotor service that do not require the useof a significantly large crane would be welcomed in the technology, andthe improved method and related system would make wind power moreeconomically competitive with other forms of power generation.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, a system for enabling servicing of a rotor of a windturbine has a rotor blade sling with at least one strap configured to beplaced over the top of a rotor blade in a ten o'clock position or a twoo'clock position. One or more rigid bars extend from the hub and outaway from the hub, and the one or more rigid bars are coupled to the atleast one strap. One or more support straps are coupled to the at leastone strap, and the one or more support straps are configured to coupleand support a rotor blade in a six o'clock position.

In another aspect, a system for enabling servicing of a rotor of a windturbine has a rotor blade sling with at least one strap placed over thetop of a rotor blade in a ten o'clock position or a two o'clockposition. One or more rigid bars extend from the hub and out away fromthe hub, and the one or more rigid bars are coupled to the at least onestrap. One or more support straps are coupled to the at least one strap,and the one or more support straps are coupled to and support a rotorblade in a six o'clock position.

In a further aspect, a method to enable servicing of a rotor of a windturbine is provided. The method includes the steps of positioning arotor blade of the rotor in a six o'clock position, and installing arotor blade sling on the rotor by placing a loop of the rotor bladesling over at least one rabbit-eared rotor blade in at least one of aten o'clock position and a two o'clock position. The rotor blade slinghas one or more support straps that extend downward from the hub. Acoupling step couples the six o'clock rotor blade to the one or moresupport straps of the rotor blade sling.

In yet another aspect, a method for enabling servicing of a rotor of awind turbine is provided. The method includes the steps of positioning arotor blade of the rotor in a six o'clock position, and installing arotor blade sling on the rotor by positioning the rotor blade sling overat least one rabbit-eared rotor blade in at least one of a ten o'clockposition or a two o'clock position. The rotor blade sling has one ormore support straps that extend downward from the hub. A coupling stepcouples the six o'clock rotor blade to the one or more support straps ofthe rotor blade sling.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 illustrates a perspective view of one embodiment of a windturbine;

FIG. 2 illustrates a perspective view of one of the rotor blades of thewind turbine shown in FIG. 1;

FIG. 3 illustrates another perspective view of the wind turbine shown inFIG. 1, particularly illustrating a rotor blade to be removed from thewind turbine positioned in a generally vertical orientation relative toa support surface of the wind turbine and a blade sock installed ontothe rotor blade;

FIG. 4 illustrates a close-up, partial perspective view of the rotorblade and the blade sock shown in FIG. 3;

FIG. 5 illustrates a cross-sectional view of the rotor blade and bladesock shown in FIG. 4 taken about line 5-5;

FIG. 6 illustrates a top-down view of the cross-section shown in FIG. 5relative to a support surface of the wind turbine, particularlyillustrating sock cables extending from the blade sock to correspondingwinches supported on and/or adjacent to the support surface;

FIG. 7 illustrates a similar cross-sectional view to that shown in FIG.5, particularly illustrating another embodiment of a blade sock inaccordance with aspects of the present subject matter;

FIG. 8 illustrates a similar cross-sectional view to that shown in FIG.5, particularly illustrating a further embodiment of a blade sock inaccordance with aspects of the present subject matter;

FIG. 9 illustrates another perspective view of the wind turbine shown inFIG. 3, particularly illustrating the rotor blade to be removed after ithas been lowered from the hub by an initial vertical distance;

FIG. 10 illustrates a close-up, partial perspective view of the rotorblade and the hub shown in FIG. 9, particularly illustrating oneembodiment of a lowering system including support cables secured to therotor blade and extending through both a pitch bearing of the windturbine and corresponding cable translation devices positioned withinthe hub;

FIG. 11 illustrates a cross-sectional view of the rotor blade and thepitch bearing shown in FIG. 10 prior to the rotor blade being loweredfrom the hub, particularly illustrating a pair of the support cables andcable translation devices of the lowering system shown in FIG. 10;

FIG. 12 illustrates a top-down view of the pitch bearing shown in FIGS.10 and 11, particularly illustrating the circumferentially positioningof the cable translation devices around the pitch bearing relative to atower reference line extending radially from the center of the windturbine tower through the center of the pitch bearing;

FIG. 13 illustrates a similar cross-sectional view to that shown in FIG.11, particularly illustrating a variation of the blade lowering systemshown in FIG. 11 in which each pair of support cables secured to therotor blade includes one support cable in operative association with acorresponding cable transition device and another support cableextending through the pitch bearing without being received within acable translation device;

FIG. 14 is a close-up, partial perspective view of the rotor blade andthe hub shown in FIG. 9, particularly illustrating another embodiment ofa lowering system including support cables secured to the rotor bladeand corresponding cable translation devices positioned within the hub;

FIG. 15 illustrates a close-up, partial perspective view of theinterface between the rotor blade and the pitch bearing shown in FIG. 14prior to the rotor blade being lowered from the hub, particularlyillustrating a support cable coupled between a support nut installedwithin the blade root and a corresponding cable translation devicepositioned within the hub;

FIG. 16 illustrates a perspective view of the support nut shown in FIG.15;

FIG. 17 illustrates an even further example of a rotor blade sling thatmay be utilized to support the rotor blade relative to the hub inaccordance with aspects of the present subject matter;

FIG. 18 illustrates an example view of one embodiment of a suitablefixture that may be utilized to couple a rotor blade sling to the bladeroot of a rotor blade in accordance with aspects of the present subjectmatter;

FIG. 19 illustrates a perspective view of a rotor blade sling that maybe utilized to support the rotor blade relative to the hub in accordancewith aspects of the present subject matter;

FIG. 20 illustrates a perspective view of a rotor servicing fixture thatmay be used to transport a rotor part to or from the rotor or hub inaccordance with aspects of the present subject matter;

FIG. 21 illustrates sequential steps of a method for servicing a rotorutilizing the rotor blade sling and rotor servicing fixture, inaccordance with aspects of the present subject matter;

FIG. 22 illustrates a perspective view of the rotor servicing fixturepartially disassembled and housed within a standard size shippingcontainer, in accordance with aspects of the present subject matter.

FIG. 23 illustrates a flowchart of a method for servicing a rotor of awind turbine, in accordance with aspects of the present subject matter;and

FIG. 24 illustrates a perspective view of the clamp assembly installedaround a portion of the blade root of a rotor blade.

FIG. 25 illustrates a top view of the clamp assembly and rotor bladeshown in FIG. 24.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

In general, the present subject matter is directed to a method andsystem for lowering a rotor blade from a hub and removing or installinga rotor part without having to use a crane to lower the entire rotor tothe ground. Specifically, as will become apparent from the descriptionprovided below, the disclosed method and system avoids the use of alarge, expensive crane capable of raising or lowering the entire rotor,thereby significantly reducing the costs associated with blade loweringand re-installation.

Referring now to the drawings, FIG. 1 illustrates a side view of oneembodiment of a wind turbine 10. As shown, the wind turbine 10 generallyincludes a tower 12 extending from a support surface 14 (e.g., theground, a concrete pad or any other suitable support surface). Inaddition, the wind turbine 10 may also include a nacelle 16 mounted onthe tower 12 and a rotor 18 coupled to the nacelle 16. The rotor 18includes a rotatable hub 20 and at least one rotor blade 22 coupled toand extending outwardly from the hub 20. For example, in the illustratedembodiment, the rotor 18 includes three rotor blades 22. However, in analternative embodiment, the rotor 18 may include more or less than threerotor blades 22. Each rotor blade 22 may be spaced about the hub 20 tofacilitate rotating the rotor 18 to enable kinetic energy to betransferred from the wind into usable mechanical energy, andsubsequently, electrical energy. For instance, the hub 20 may berotatably coupled to an electric generator (not shown) positioned withinthe nacelle 16 to permit electrical energy to be produced.

Referring now to FIG. 2, a perspective view of one of the rotor blades22 shown in FIG. 1 is illustrated in accordance with aspects of thepresent subject matter. As shown, the rotor blade 22 includes a bladeroot 24 configured for mounting the rotor blade 22 to the hub 20 of awind turbine 10 and a blade tip 26 disposed opposite the blade root 24.A body 28 of the rotor blade 22 may extend lengthwise between the bladeroot 24 and the blade tip 26 and may generally serve as the outer shellof the rotor blade 22. As is generally understood, the body 28 maydefine an aerodynamic profile (e.g., by defining an airfoil shapedcross-section, such as a symmetrical or cambered airfoil-shapedcross-section) to enable the rotor blade 22 to capture kinetic energyfrom the wind using known aerodynamic principles. Thus, the body 28 maygenerally include a pressure side 30 and a suction side 32 extendingbetween a leading edge 34 and a trailing edge 36. Additionally, therotor blade 22 may have a span 38 defining the total length of the body28 between the blade root 24 and the blade tip 26 and a chord 40defining the total length of the body 28 between the leading edge 34 andthe trailing edge 36. As is generally understood, the chord 40 may varyin length with respect to the span 38 as the body 28 extends from theblade root 24 to the blade tip 26.

Moreover, as shown in FIG. 2, the rotor blade 22 may also include aplurality of T-bolts or root attachment assemblies 42 for coupling theblade root 24 to the hub 20 of the wind turbine 10. In general, eachroot attachment assembly 42 may include a barrel nut 44 mounted within aportion of the blade root 24 and a root bolt 46 coupled to and extendingfrom the barrel nut 44 so as to project outwardly from a root end 48 ofthe blade root 24. By projecting outwardly from the root end 48, theroot bolts 46 may generally be used to couple the blade root 24 to thehub 20 via a pitch bearing 150 of the wind turbine 10. For example, thepitch bearing 150 may define a plurality of bolt holes 151 configured toreceive the root bolts 46. Additionally, as will be described below, aportion of such root bolts 46 may also be utilized when the rotor blade22 is being lowered or removed from and/or re-installed onto the hub 20.

It should be appreciated that, although the methods will generally bedescribed with reference to lowering a rotor blade 22 from the hub 20 ofwind turbine 10, the various method steps and system componentsdisclosed herein may similarly be used to re-install the rotor blade 22onto the hub 20 by simply reversing the order in which the method isperformed. It should also be appreciated that, although the methods willbe described herein as being performed in a particular order, themethods may generally be performed in any suitable order that isconsistent with the disclosure provided herein.

Referring particularly to FIG. 3, the rotor blade 22 to be lowered maybe initially rotated to a vertically downward position (e.g., a 6o'clock position) such that the blade 22 has a generally verticalorientation relative to the support surface 14 of the wind turbine 10.For example, as shown in FIG. 3, the rotor blade 22 is extendingvertically downward from the hub 20 such that the blade tip 26 ispointing towards the support surface 14. It should be appreciated that,due to a tilt angle and/or cone angle of the wind turbine 10, the rotorblade 22 may be angled slightly away from the tower 12 when moved to thevertically downward position.

In several embodiments, once the rotor blade 22 is rotated to thevertically downward position, a blade sock 100 may be installed onto theblade 22 at an intermediate location 102 defined between the blade root24 and the blade tip 26. In one embodiment, the intermediate location102 may correspond to a location defined along an outboard section ofthe rotor blade 22, such as at a location spaced apart from the bladeroot 24 by a distance 104 that is greater that about 50% of the bladespan 38. For example, the distance 104 may range from about 50% of thespan 38 to about 95% of the span 38, such as from about 65% of the span38 to about 95% of the span 38 or from about 75% of the span 38 to about90% of the span 38 and any other subranges therebetween.

As shown in FIG. 3, to install the blade sock 100 onto the rotor blade22, one or more lift cables 106 may be secured to the blade sock 100 andmay extend upward to an up-tower location, such as at a location onand/or within the hub 20 or the nacelle 16. For instance, in oneembodiment, the lift cable(s) 106 may extend upward from the blade sock102 to personnel located within and/or on top of the hub 20 or thenacelle 16. Regardless, the lift cable(s) 106 may be used to lift theblade sock 100 vertically upwards relative to the support surface 14 toallow the sock 100 to be installed around the rotor blade 22 at theintermediate location 102. For instance, as will be described below, theblade sock 100 may define a closed shape configured to extend around theentire outer perimeter of the rotor blade 22. Thus, when lifting theblade sock 100 via the lift cable(s) 102, the sock 100 may be carefullyaligned with the rotor blade 22 such that the blade tip 26 is receivedwithin the sock 100.

Additionally, one or more sock cables 108, 110 may also be coupled tothe blade sock 100 and may extend downward to a location adjacent to thesupport surface 14. For instance, in the illustrated embodiment, thesystem includes a first sock cable 108 and a second sock cable 110coupled between the blade sock 100 and corresponding winches 112disposed on and/or adjacent to the support surface 14. The sock cables108, 110 may, for example, be utilized to assist in aligning the bladesock 100 with the rotor blade 22 as the sock 100 is being lifted up ontothe blade 22 via the lift cables 106. In addition, as will be describedbelow, the sock cable(s) 108, 110 may also be used as a means fortightening the blade sock 100 around the rotor blade 22 at theintermediate location 102 and/or for applying a force through the bladesock 100 in order to adjust and/or control the orientation of the rotorblade 22 as it is being lowered below the hub 20.

Referring now to FIGS. 4-6, differing views of one embodiment of theblade sock 100 described above are illustrated in accordance withaspects of the present subject matter. Specifically, FIG. 4 illustratesa close-up, perspective view of the blade sock 100 installed onto therotor blade 22 at the intermediate location 102 with the lift cables 106being removed and FIG. 5 illustrates a cross-sectional view of the bladesock 100 shown in FIG. 4 taken about line 5-5. Additionally, FIG. 6illustrates top-down view of the cross-section shown in FIG. 5,particularly illustrating the sock cables 108, 110 extending from theblade sock 100 to corresponding winches 112 disposed on and/or adjacentto the support surface 14.

As particularly shown in FIGS. 4 and 5, the blade sock 100 may include asock strap 114 generally defining a closed shape configured to extendaround the outer perimeter of the rotor blade 22. In addition, the bladesock 100 may include one or more edge supports 116, 118 positionedbetween the sock strap 114 and the rotor blade 22. For example, as shownin the illustrated embodiment, the blade sock 100 includes both aleading edge support 116 positioned between the sock strap 114 and therotor blade 22 around the location of the leading edge 34 of the blade22 and a trailing edge support 118 positioned between the sock strap 114and the rotor blade 22 around the location of the trailing edge 36 ofthe blade 22.

In general, the sock strap 114 may be configured to be tightened aroundthe outer perimeter of the rotor blade 22 in order to secure the bladesock 100 to the blade 22 at the intermediate location 102. In severalembodiments, the sock strap 114 may be configured to be self-tightening.For example, as shown in FIG. 5, the sock strap 114 may extendlengthwise between a first end 120 and a second end 122. In addition,the sock strap 114 may include suitable coupling mechanisms (e.g., mountrings or hooks or any other suitable coupling device) positioned at theends 120, 122 of the strap 114 for coupling each end 120, 122 to one ofthe sock cables 108, 110. Specifically, as shown in FIG. 5, a firstmount ring 124 may be secured to the first end 120 of the sock strap 114and a second mount ring 126 may be secured to the second end 122 of thesock strap 114. In such an embodiment, the sock strap 114 may beconfigured to be looped around the outer perimeter of the rotor blade 22in a partially overlapping manner such that the first mount ring 124 isdisposed on one side of the rotor blade 22 (e.g., the pressure side 30)and the second mount ring 126 is disposed on the opposite side of therotor blade 22 (e.g., the suction side 32). As such, when the sockcables 108, 110 are coupled to the mount rings 124, 126 and subsequentlypulled or otherwise tensioned (e.g., via the winches 112) so as to applya tightening force at each end 120, 122 of the sock strap 114 (indicatedby arrows 128 in FIG. 5), the strap 114 may be configured to tightenaround the outer perimeter of the rotor blade 22, thereby securing theblade sock 100 to the rotor blade 22.

The edge supports 116, 118 of the blade sock 100 may generallycorrespond to any suitable rigid support-type members configured toprevent damage to the leading and trailing edges 34, 36 of the rotorblade 22 as the sock strap 114 is tightened around the blade 22 and/oras the blade sock 100 is used to at least partially support the weightof the rotor blade 22 (as will be described below). For example, asshown in FIG. 5, the leading edge support 116 may include side portions134 configured to extend along portions of the pressure and suctionsides 30, 32 of the rotor blade 22 and may also include an edge portion(indicated by bracket 136) extending between the side portions 134around leading edge 34. Specifically, the edge portion 136 may beconfigured to define a curved profile generally corresponding to thecurved profile of the leading edge 34 of the blade 22 such that the edgeportion 136 wraps around and provides a nesting configuration for theleading edge 34. Similarly, the trailing edge support 118 may includeside portions 138 configured to extend along portions of the pressureand suction sides 30, 32 of the rotor blade 22 and may also include anedge portion (indicated by bracket 140) extending between the sideportions 138 around the trailing edge 36. However, unlike the edgeportion 136 of the leading edge support 116, the edge portion 140 may beconfigured to extend around the trailing edge 36 such that a gap isdefined between the trailing edge 36 and the corresponding support 116,thereby providing a buffer to prevent compression forces applied via thetightened sock strap 114 from being directed through the trailing edge36.

It should be appreciated that the edge supports 116, 118 may generallybe configured to be formed from any suitable rigid material. Forinstance, in one embodiment, the edge supports 116, 118 may be formedfrom a fiber-reinforced laminate composite, such as a carbon and/orglass fiber-reinforced laminate. Alternatively, the edge supports 116,118 may be formed from any other suitable rigid material, such as anysuitable metal and/or any suitable rigid polymer-containing material.Additionally, in several embodiments, for the portions of the edgesupports 116, 118 configured to contact the outer surface of the rotorblade 22, the edge supports 116, 118 may include an inner layer (notshown) formed from a suitable cushioning material in order to protectthe blade's outer surface. For instance, the inner layer may be formedfrom a foamed material or any other suitable soft and/or cushioningmaterial.

It should also be appreciated that, although the edge supports 116, 118are shown in the illustrated embodiments as two separate components, theedge supports 116, 118 may, instead, be configured as a single componentconfigured to extend around the entire outer perimeter of the rotorblade 22. Additionally, in alternative embodiments, the blade sock 100may only include one of the edge supports 116, 118, such as by onlyincluding the trailing edge support 118.

Referring to FIG. 6, as indicated above, the sock cables 108, 110 may,in one embodiment, be configured to be coupled between the blade sock100 and corresponding winches 112 disposed on and/or adjacent to thewind turbine's support surface 14. In such an embodiment, thepositioning of the winches 112 relative to the position of the rotorblade 22 (as mounted on the hub 20) may be selected to ensure that thewinches 112 are spaced sufficiently apart from the rotor blade 22 toallow for the orientation of the blade 22 to be adjusted and/orcontrolled as it is lowered from the hub 20. For example, as shown inFIG. 6, the winches 112 may be positioned a horizontal distance 142 fromthe rotor blade 22, which may vary depending on the overall length ofthe blade's span 38. In addition, the winches 112 may be spaced apartfrom one another in a cross-wise direction such that each sock cable108, 110 extends from the blade sock 100 at a given cable angle. Forinstance, in one embodiment, the cable angle 144 may range from about 30degrees to about 60 degrees, such as from about 35 degrees to about 55degrees or from about 42 degrees to about 48 degrees and any othersubranges therebetween.

It should be appreciated that, as an alternative to the winches 112, thesock cables 108, 110 (which may also be referred to as tag lines) may becoupled to and/or held in position by any other suitable device, objectand/or person positioned on and/or adjacent to the support surface 13.For instance, in one embodiment, sock cables 108, 110 may simply be heldby personnel standing on the support surface 14.

It should be appreciated that, in alternative embodiments, the sockstrap 114 may have any other suitable configuration that allows it to betightened around the rotor blade 22 using the sock cables 108, 110. Forinstance, instead of being looped around the rotor blade 22 in thepartially overlapping manner shown in FIG. 5, the sock strap 114 may beconfigured similar to a choker-type lifting sling. An example of such aconfiguration is illustrated, for example, in FIG. 7. As shown in FIG.7, the sock strap 114 may be configured to be looped around the rotorblade 22 once, with the first end 120 of the sock strap 114 beingreceived through the mount ring 126 secured to the second end 122 of thestrap 114. In such an embodiment, by coupling one of the sock cables(e.g., the first sock cable 108) to the first end 120 of the strap 114,the sock cable 108 may be used to apply a tightening force through thesock strap (as indicated by arrow 128) in order to tighten the sockstrap 114 around the rotor blade 22.

Alternatively, FIG. 8 illustrates yet another example of a choker-typeconfiguration that may be utilized to allow the sock strap 114 to beself-tightening. As shown, the sock strap is formed from two separatestrap portions 114A, 114B. Specifically, the first strap portion 114Amay be configured to extend partially around the outer perimeter of therotor blade 22 between first and second mount rings 124, 126. Inaddition, the second strap portion 114B may be configured to extendaround the remainder of the outer perimeter of the rotor blade 22. Insuch an embodiment, each end of the second strap portion 114B may bereceived through one of the mount rings 124, 126 of the first strapportion 114A and coupled to one of the sock cables 108, 110. Thus, eachsock cable 108, 110 may be used to apply a tightening force (asindicated by arrows 128) through the first and second strap portions114A, 114B that allows the sock strap to be tightened around the rotorblade 22.

It should be appreciated that the sock strap 114 (including strapportions 114A, 114B) may generally be formed from any suitablematerial(s) that allow the strap 114 to function as described herein.For instance, in several embodiments, the sock strap 114 may be formedfrom a relative strong and/or durable material, such as nylon, Kevlar orany other suitable material typically utilized to form lifting strapsand/or slings.

Referring now to FIG. 9, once the blade sock 100 is installed onto therotor blade 22 at the intermediate location 102, the rotor blade 22 maybe initially lowered from the hub 22. Specifically, as shown in FIG. 9,the rotor blade 22 may be lowered from the hub 20 by an initial verticaldistance 146. As will be described below, such initial lowering of therotor blade 22 may allow for one or more straps, cables or chains to becoupled between the blade 22 and another up-tower component of the windturbine 10, thereby providing a means for further lowering the rotorblade 22. Thus, the initial vertical distance 146 may generallycorrespond to any suitable distance that allows for the installation ofthe straps, cables or chains and any associated harness. For example, inone embodiment, the initial vertical distance 146 may generally rangefrom about 2 feet to about 15 feet, such as from about 3 feet to about10 feet or from about 5 feet to about 10 feet and any other subrangestherebetween.

Referring now to FIGS. 10-12, one embodiment of suitable components thatmay be included within a lowering system to initially lower the rotorblade 22 from the hub 20 is illustrated in accordance with aspects ofthe present subject matter. Specifically, FIG. 10 illustrates a partialperspective view of the hub 20, the rotor blade 22 and the pitch bearing150 of the wind turbine 10 after the blade 22 has been lowered from thehub 20 by the initial vertical distance 146. FIG. 11 illustrates apartial, cross-sectional view of the interface between the rotor blade22 and the pitch bearing 150 prior to the blade 22 being loweredrelative to the hub 20. Additionally, FIG. 12 illustrates a top view ofthe pitch bearing 150 of the wind turbine 10, particularly illustratingthe relative circumferential positioning of the system componentsutilized to initially lower the rotor blade 22 relative to the hub 20.

It should be appreciated that, for purposes of illustration, only theinner race of the pitch bearing 150 is shown in FIG. 12. As is generallyunderstood, the pitch bearing 150 may also include an outer raceconfigured to be coupled to the hub 20. As such, when the inner race isrotated relative to the outer race of the pitch bearing 150, the rotorblade 22 may be pitched about its pitch axis.

As particularly shown in FIG. 11, to allow the rotor blade 22 to beinitially lowered, several of the root bolts 46 extending through thebolt holes 151 defined in the pitch bearing 150 may be removed andreplaced with suitable support cables 152. For example, as shown in FIG.10, in one embodiment, eight of the root bolts 46 may be removed andreplaced with corresponding support cables 152. In doing so, theremainder of the root bolts 46 may be initially maintained in engagementwith the pitch bearing 150 (e.g., via suitable attachment nuts (notshown)) to allow the rotor blade 22 to continue to be supported by thehub 20 until the rotor blade 22 is ready to be lowered.

In general, the support cables 152 may correspond to any suitable cablesthat are capable of supporting the weight of the rotor blade 22 as it isbeing lowered relative to the hub 20. For example, in severalembodiments, each support cable 152 may correspond to a steel cable orany other suitable wire rope that has a rated load capacity sufficientto handle the weight of the rotor blade 22. In another embodiment, eachsupport cable 152 may correspond to a metal chain or any other suitableelongated cable-like object. Moreover, it should be appreciated thateach support cable 152 may generally be configured to define anysuitable length that permits the cables to be utilized to lower therotor blade 22 away from the hub 20 by the initial vertical distance146.

In addition, the support cables 152 may generally be configured to becoupled to the rotor blade 22 using any suitable attachment means. Forexample, as shown in the illustrated embodiment, a stud end 154 of eachcable 152 may be coupled to a threaded cable stud 156 configured to bescrewed into one of the barrel nuts 44 extending within the blade root24. In such an embodiment, a swaged or other suitable connection may beformed between the stud end 154 of each cable 152 and each cable stud156 to securely couple to the cables 152 to the corresponding studs 156.In other embodiments, the support cables 152 may be coupled to the bladeroot 24 using any other suitable means, such as by coupling each supportcable 152 to a suitable mounting fixture configured to be secured to theblade root 24.

It should be appreciated that, in embodiments in which the supportcables 152 are coupled to the blade root 24 via the threaded cable studs156, each cable stud 156 may generally be configured to define anysuitable length 157. As shown in FIG. 11, in one embodiment, the length157 of each cable stud 156 may be substantially equal to a correspondinglength 159 of the root bolts 46.

As shown in FIGS. 10 and 11, each support cable 152 may be configured tobe in operative association with a suitable cable translation device 158positioned within the hub 20. In general, each cable translation device158 may correspond to any suitable device that allows for the rotorblade 22 to be safely and securely moved relative to the hub 20 usingthe support cables 152. For example, in several embodiments, each cabletranslation device 152 may correspond to a fluid-driven actuator (e.g.,a hydraulic or pneumatic actuator) configured to be in operativeassociation with a corresponding support cable 152 to allow the rotorblade 22 to be lowered and/or raised relative to the hub 20.

Specifically, in a particular embodiment of the present subject matter,each cable translation device 158 may be configured as a hollowlifting/lowering cylinder or as a single strand jack designed toincrementally lower and/or raise the rotor blade 22. For example, asshown in FIG. 11, each device 158 may include a cylinder 160 configuredto be coupled to the pitch bearing 150 (e.g., via suitable bolts and/orother mechanical fasteners (not shown)) and a hollow piston 162configured to receive one of the support cables 152. The piston 162 maygenerally be configured to be actuated and retracted relative to thecylinder 160 by supplying/expelling a pressurized fluid to/from thecylinder 160 (e.g., via fluid port 164). In addition, each cabletranslation device 158 may include an upper clamping mechanism 166positioned directly above the piston 162 and a lower clamping mechanism168 positioned directly below the piston 162. As is generallyunderstood, the upper and lower clamping mechanisms 166, 168 may beconfigured to alternatively clamp the support cable 152 as the piston162 is actuated and retracted, thereby allowing each translation device158 to lower or raise the rotor blade 22 in short increments with eachactuation/retraction of the piston 162.

Additionally, in several embodiments, a stop block 170 may be configuredto be installed around each support cable 152 directly above itscorresponding cable translation device 158. In general, each stop block170 may be configured to serve as a built-in safety feature providing amechanical stop for each support cable 152 in the event of failure ofone of the cable translation devices 158. For example, as particularlyshown in FIG. 11, each support cable 152 may include a plurality of lugs172 spaced apart incrementally along the cable's length. In such anembodiment, an opening or slot (not shown) may be defined through eachstop block 170 that is dimensionally larger than the cable 152, therebyallowing the cable 152 to pass through the stop block 170 as it is beinglowered relative to the translation device 158. However, given theirincreased size, the lugs 172 may not be capable of passing through theopening or slot defined in each stop block 170. Accordingly, in theevent of failure of one of the cable translation devices 158, the lug172 positioned immediately above the corresponding stop block 170 maycome into contact with and engage an upper surface of the block 170,thereby preventing further motion of the support cable 152 relative tothe translation device 158. In contrast, during normal operation, thestop blocks 170 may be continuously repositioned along the support cable152 as each lug 172 is lowered down onto and/or adjacent to itscorresponding stop block 170. For example, as indicated by the dashedlines in FIG. 11, when one of the lugs 172 is lowered down into and/oradjacent to one of the stop blocks 170, the stop block 170 may beremoved from the support cable 152 and repositioned above such lug 172to allow the support cable 152 to continue to be lowered through thetranslation device 158.

It should be appreciated that, in general, each support cable 152 andcorresponding translation device 152 may be configured to be installedat any suitable location around the circumference of the blade root 24and pitch bearing 150. However, in several embodiments, thecables/devices 152, 158 may be grouped in pairs spaced apart around theblade root 24 and pitch bearing 150. For example, as shown in FIG. 12,in one embodiment, each pair of the cable translation devices 158 may beconfigured to be positioned around the pitch bearing 150 atcircumferential locations generally adjacent to a reference line 174oriented perpendicularly to a tower reference line 176 extendingradially from the center of the wind turbine's tower 12 through thecenter of the pitch bearing 150. Specifically, as shown, each pair ofthe cable translation devices 158 may generally be spaced apartcircumferentially from the reference line 174 by an angle 178 equal toless than about 45 degrees, such as less than about 40 degrees or lessthan about 35 degrees. Of course, in such an embodiment, the supportcables 152 may similarly be secured to the blade root 24 atcorresponding circumferential location relative to the reference line174. Such positioning of the cables/devices 152, 158 adjacent to thereference line 174 may, in certain rotor blade configurations, allow forthe rotor blade 22 to be slightly angled away from the tower 12 as theblade 22 is being lowered relative to the hub 20 due to the location ofthe blade's center of gravity.

As indicated above, in one embodiment, eight support cables 152 andcorresponding translation devices 158 may be installed to assist inlowering the rotor blade 22 relative to the hub 20. However, in otherembodiments, any other suitable number of support cables 152 andtranslation devices 158 may be utilized to lower the rotor blade 22relative to the hub 20. For instance, in one embodiment, the rotor blade22 may be lowered using only four cables/devices 152, 158 or using onlytwo cables/devices 152, 158.

Additionally, in other embodiments, only a portion of the support cables152 coupled to the rotor blade 22 may be configured to be in operativeassociated with corresponding cable translation devices 158. Forinstance, FIG. 13 illustrates an alternative embodiment to theembodiment shown in FIG. 11. As shown in FIG. 13, for each pair ofsupport cables 152 extending from the blade root 24, one of the cables152 may be configured to be in operative association with acorresponding translation device 158 positioned within the hub 20. Insuch an embodiment, each support cable 152 not associated with atranslation device 158 may simply be used to provide additional supportfor the rotor blade 22 as it is being lowered. In addition, such supportcables 152 may also be configured to be utilized in connection with thestop blocks 170 described above. For instance, as shown in FIG. 13, thestop block 170 may be positioned directly above the pitch bearing 150 toallow the stop block 170 to be engaged between one of the cable lugs 172and the pitch bearing 150 in the event of failure of one or more of thetranslation devices 158 installed on any of the other support cables152.

It should be appreciated that, in further embodiments of the presentsubject matter, the rotor blade 22 may be configured to be initiallylowered from the hub 20 using any other suitable lowering means known inthe art. For instance, as an alternative to the fluid-driven cabletranslation devices 158 described above, the cable translation devicesmay correspond to winches positioned within the hub 20. In such anembodiment, the support cables (or chains) 152 may be unwound from eachassociated winch in order to initially lower the rotor blade 22 from thehub 20. In another embodiment, the support cables 152 may be replacedwith elongated threaded rods. In such an embodiment, the threaded rodsmay be received within a suitable translation device (e.g., a screwjack) configured to allow the rods to be moved relative to the device,thereby allowing the rotor blade 22 to be lowered relative to the hub20.

Referring now to FIGS. 14-16, another embodiment of suitable componentsthat may be included within a lowering system to initially lower therotor blade 22 from the hub 20 is illustrated in accordance with aspectsof the present subject matter. Specifically, FIG. 14 illustrates apartial perspective view of the hub 20, the rotor blade 22 and the pitchbearing 150 of the wind turbine 10 after the blade 22 has been loweredfrom the hub 20 by the initial vertical distance 146. FIG. 15illustrates a partial, perspective view of the interior of the hub 20 atthe interface between the rotor blade 22 and the pitch bearing 150 priorto the blade 22 being lowered relative to the hub 20. Additionally, FIG.16 illustrates a perspective view of one embodiment of a modifiedbarrel-type support nut 300 configured for use in the illustratedlowered system in accordance with aspects of the present subject matter.

As particularly shown in FIGS. 14 and 15, to allow the rotor blade 22 tobe initially lowered, several of the root bolts 46 extending through thebolt holes 151 defined in the pitch bearing 150 may be removed. Theexisting barrel nuts 44 associated with such bolts 46 may then bereplaced with cylindrically-shaped support nuts 300, with each supportnut 300 being configured to allow a corresponding support cable 302 tobe coupled to the blade root 24. For example, as shown in FIG. 14, inone embodiment, four of the existing barrel nuts 44 may be removed andreplaced with suitable support nuts 300. In doing so, the remainder ofthe root bolts 46 may be initially maintained in engagement with thepitch bearing 150 (e.g., via suitable attachment nuts 304 to allow therotor blade 22 to continue to be supported by the hub 20 until the rotorblade 22 is ready to be lowered.

It should be appreciated that the support nuts 300 may generally haveany suitable configuration that allows each support nut 300 to beinserted through the blade root 24 in place of one of the existingbarrel nuts 44 as well as to provide a means for coupling each supportcable 302 to the rotor blade 22. For example, in one embodiment, eachsupport nut 300 may be configured as a modified barrel nut. Forinstance, as shown in FIG. 16, each support nut 300 may include athreaded opening 306 extending vertically through the support nut 300 toallow a corresponding root bolt 46 or other suitable threaded member tobe coupled to the nut 300 and extend vertically therefrom. In addition,each support nut 300 may include a laterally extending threaded opening308 defined through one of the sides of the nut 300. The opening 308 mayallow for a suitable coupling device 310 (e.g., a swivel eye, mountring, mount hook or any other suitable attachment mechanism) to besecured to the support nut 300 for coupling each support cable 302 tothe rotor blade 22.

As indicated above, in one embodiment, four support nuts 300 may beinstalled through the blade root 24 in place of the existing barrel nuts44 to allow four corresponding support cables 302 to be coupled to therotor blade 22. However, in other embodiments, any other suitable numberof support nuts 300 may be secured within the blade root 24 to provide ameans for coupling a corresponding number of support cables 302 to therotor blade 22, such as by installing less than four support nuts 300within the blade root 24 (e.g., two or three support nuts) or greaterthan four support nuts 300 within the blade root 24 (e.g., five, six ormore support nuts).

Additionally, it should be appreciated that the support nuts 300 may beconfigured to be maintained in position relative to the rotor blade 22using any suitable attachment means. For instance, in one embodiment,once a given support nut 300 is inserted within the blade root 24, acorresponding root bolt 46 may be inserted through the pitch bearing 150and screwed into the vertically extending opening 306 of the support nut300 in order to secure the nut 300 within the blade root 24.Alternatively, as shown in FIG. 15, an alignment pin 312 may beconfigured to be inserted through the pitch bearing 150 and screwed intothe vertically extending opening 306 of each support nut 300. In such anembodiment, each alignment pin 312 may generally be configured forattachment within the corresponding support nut 300 in a manner similarto the existing root bolts 46 and, thus, may include a threaded end 314for engaging the threaded opening 306 of the support nut 300. Eachalignment pin 312 may define a vertical height or length 316 that isgreater than the length 159 of the root bolts 46. Accordingly, thealignment pins 312 may also be utilized to align the rotor blade withpitch bearing as the rotor blade (or a different rotor blade with thealignment pins installed therein) is being lifted up onto the hub.

In a further embodiment, the support nuts 300 may be secured within theblade root 24 using the threaded cable studs 156 of the support cables152 described above with reference to FIGS. 10-13. In such anembodiment, the support cables 152 may be utilized as additional safetyfeatures for the system as the rotor blade 22 is being lowered relativeto the hub 20. For example, as described above with reference to FIG.13, the disclosed stop blocks 170 may be utilized without the cabletranslation devices 158 to allow each block 170 to serve as a mechanicalstop between the pitch bearing 150 and the adjacent lugs 172 of thesupport cables 152 as the rotor blade 22 is being lowered.

It should also be appreciated that each support nut 300 may generally beconfigured to be installed within the rotor blade 22 at any suitablecircumferential location around the blade root 24. However, in severalembodiments, the support nuts 300 may be configured to be installed atthe same or similar locations to the circumferential locations for thecables/devices 152/158 described above with reference to FIG. 12. Forinstance, in one embodiment, the support nuts 300 may be configured tobe installed within the blade root 24 at circumferential locationsspaced apart from the reference line 174 by a given angle 178 (FIG. 12),wherein the angle is generally equal to less than about 45 degrees.

Each support cable 302 may be configured to extend from one of thesupport nuts 300 to a corresponding cable translation device 318positioned within the hub 20. As shown in FIG. 15, in one embodiment,the cable translation device 318 may correspond to cable hoists(including chain hoists) configured to be mounted to and/or supported byany suitable wind turbine component(s) positioned within the hub 20(e.g., the hub gusset(s), joist(s) and/or any other suitablecomponent(s)). As is generally understood, cable hoists may beconfigured to allow suitable cables to be passed therethrough in acontrolled manner. Thus, in the present application, such cable hoistsmay be utilized to safely and effectively lower the rotor blade 22relative to the hub 20.

It should be appreciated that, in alternative embodiments, the cabletranslation devices 318 may correspond to any other suitable devicesand/or mechanisms that allow for the rotor blade 22 to be loweredrelative to the hub 20 via the corresponding support cables 302. Forinstance, in another embodiment, the cable translation devices 318 maycorrespond to winches positioned within the hub 20.

It should also be appreciated that, similar to the support cables 152described above, each support cable 302 may generally correspond to anysuitable elongated cable-like object that has a rated load capacitysufficient to handle the weight of the rotor blade 22. For instance, asshown in the illustrated embodiment, the support cables 302 areconfigured as metal chains. However, in other embodiments, the supportcables 302 may correspond to steel cables or any other suitable wireropes. Moreover, it should be appreciated that each support cable 302may generally be configured to define any suitable length that permitsthe cables 302 to be utilized to lower the rotor blade 22 away from thehub 20 by the initial vertical distance 146. The support cables 302 mayalso be connected to blade 22 by cutting a hole into the blade root 24to install an attachment to the root bolts 46.

Referring now to FIG. 17, a harness arrangement is illustrated inaccordance with aspects of the present subject matter. First and secondsupport straps 214, 216 are supported by a first strap 220, second strap222 and bars 218 that extend around the remaining “rabbit-eared” rotorblades 22. In such an embodiment, first and second support straps 214,216 may be configured to be coupled to the rotor blade 22 via mountingblocks 202. Additionally, a rigid structure may also be installed ontoand/or around the remaining rotor blades 22 to provide additionalsupport for the support straps 214, 216 and/or to maintain the spacingdefined between the straps 214, 216 and the hub 20. For example, asshown in FIG. 17, a pair of rigid bars 218 (one bar from each pair beingshown) may be supported adjacent to the blade root 24 of each remainingrotor blade 22 using first and second straps 220, 222 configured toextend over and around portions of the blade root 24, the pitch bearing150 and/or the hub 20. In such an embodiment, a suitable coupling device224 (e.g., a mounting ring or eyelet) may be positioned or formed at theoutboard end of each rigid bar 218 for receiving the adjacent supportstrap 214, 216. The straps 220, 222, bars 218 and support straps 216,218 may be referred to as a rotor blade sling or rotor blade harness.The rotor blade sling is coupled to the rotor blade 22 and then thetranslation devices 318 may be operated to further lower the rotor blade22 by a little more so that the rotor blade sling at least partially, ifnot fully, supports the rotor blade 22. At this point, the supportcables 302 can be removed and the rotor blade sling will fully supportthe rotor blade 22.

FIG. 18 illustrates a side view of one embodiment of a suitable mountingfixture 200 for coupling the support straps 214, 216 to the blade root24 of rotor blade 22. As shown, the fixture 200 may include a mountblock 202 defining a plurality of bolt holes 204 (e.g., two along eachside of the fixture 200) configured to receive the root bolts 46. Thus,when the fixture 200 is installed onto the rotor blade 22 such that abottom surface 206 of the fixture 200 is contacting the root end 48 ofthe blade 22, a corresponding number of root bolts 46 may extend throughthe bolt holes 204 to allow the fixture 200 to be coupled to the rotorblade 22 (e.g., via suitable attachment nuts 208). Support straps 214,216 may include hooks 212 that engage a loop 210 connected to mountblock 202.

FIG. 19 illustrates a perspective view of the rotor blade sling 1900,according to an aspect of the present invention. The rotor blade sling1900 is configured to be positioned on the rotor and slip over one ofthe “rabbit-eared” rotor blades (e.g., at 10 o'clock and 2 o'clock). Thesupport straps 216 hang down to connect to and support the 6 o'clockrotor blade. A top strap 1910 may be connected to the first strap 220and second strap 222. The bars 218 provide support to the rotor bladesling. The support straps 216 are removably connected to the couplingdevices 224. If desired, the rotor blade sling may also include cushions1920 to protect the rabbit-eared rotor blades during use of the rotorblade sling.

FIG. 20 illustrates a perspective view of a rotor servicing fixture2000, according to an aspect of the present invention. The rotorservicing fixture 2000 is configured to be inserted between the rotorblade and the hub, and is also configured to transport a rotor part toor from the rotor via a crane. The crane can be a crane that does nothave the capacity to lift the entire rotor 18 or rotor blade 22, andthis is one of the advantages because smaller cranes are much morewidely available and are also less expensive than larger cranes whichcould support the entire rotor 18. The rotor part to be transported maybe a pitch bearing, stiffening ring, pitch motor, battery box, controlbox, or any other item that may be used in the hub 20 or rotor 18.

The rotor servicing fixture 2000 may be generally C-shaped so that itcan fit around the hub 20, and includes three sections, a lower section2001, a middle section 2002 and a top section 2003, each of which areconfigured to attach to form the C-shaped rotor servicing fixture 2000.The lower section 2001 includes one or more legs 2010 that areconfigured to maintain the rotor servicing fixture 2000 in an uprightposition when the rotor servicing fixture is resting on the ground. Thelegs 2010 may be configured in an inverted “Y” shape (as shown), aninverted “T” shape, or any suitable shape that adds stability to therotor servicing fixture 2000. A rotor part mounting area 2012 isgenerally Y-shaped and includes a plurality of part mounting pads 2014.If the rotor part is a pitch bearing, then the pitch bearing can bearranged to rest on these mounting pads 2014, and the mounting pads mayhave extending pins or straps to aid in securing the pitch bearing tothe rotor part mounting area. This rotor part mounting area 2012 may beused to transport new or replacement rotor parts to the rotor. The rotorpart mounting area 2012 may also comprise a substantially flat and solidmounting pad (not shown) for transporting smaller items to or from therotor. The lower section 2001 may also include a padded member 2016 on ahub facing portion of the lower section, and the padded member 2016 isconfigured to protect the hub during use of the rotor servicing fixture2000. For example, the padded member may be comprised of rubber or foam,or any other resilient material that will absorb and cushion impactsbetween the rotor servicing fixture 2000 and hub 20.

The middle section 2002 consists primarily of a straight section thatfits into both the lower section 2001 and the top section 2003. Thesections may be bolted together by any suitable mechanical fasteners.The middle section 2002 may also include a padded member 2026 on a hubfacing portion of the middle section, and the padded member 2026 isconfigured to protect the hub during use of the rotor servicing fixture2000. For example and as above, the padded member may be comprised ofrubber or foam, or any other resilient material that will absorb andcushion impacts between the rotor servicing fixture 2000 and hub 20.

The top section 2003 includes a crane attachment point 2032 and/or 2033located above the rotor part mounting area 2012. The crane attachmentpoint may be located so that the rotor servicing fixture maintains arelatively level orientation during use, as this will help to avoidundesired impacts between the rotor servicing fixture 2000 and parts ofthe rotor 18. To further fine tune the balance of the rotor servicingfixture 2000, a counterweight 2034 may be located and attached near theend of the top section. The weights of the counterweight 2034 are easilyreplaced or added to fine tune the balance of the rotor servicingfixture 2000. As above, the top section may include a padded member 2036that is configured to protect the hub during use of the rotor servicingfixture, and the padded member may be comprised of rubber or foam, orany other resilient material that will absorb and cushion impactsbetween the rotor servicing fixture 2000 and hub 20. The rotor servicingfixture could also be a cantilevered or balanced support device, asopposed to a generally C-shaped member.

FIG. 21 illustrates sequential steps of a method for servicing a rotor,according to an aspect of the present invention. In the upper left, therotor blade 22 has been lowered by support cables 302 (see FIG. 14). Thesupport straps 216 of the rotor blade sling 1900 have also been attachedto the rotor blade 22. The upper right illustrates that the supportcables 302 have been removed and the entire weight of the rotor blade 22is supported by the rotor blade sling 1900. In this example, the 6o'clock rotor blade is lowered about 6 to 10 feet below the pitchbearing 150 or hub 20. The lower right portion illustrates a side viewshowing the rotor servicing fixture placed between the 6 o'clock rotorblade and the hub 20. At this point, the rotor part may be removed fromthe hub 20 and lowered onto the rotor servicing fixture 2000. The lowerleft illustrates the rotor part (e.g., pitch bearing 150) mounted on therotor servicing fixture 2000 and the rotor servicing fixture may now belowered down to the ground by a crane (not shown for clarity).

FIG. 22 illustrates a perspective view of the rotor servicing fixture2000 partially disassembled and housed within a standard size shippingcontainer 2200, according to an aspect of the present invention. Therotor servicing fixture 2000 is configured to be modular so that it maybe easily assembled or disassembled in the field, and further it mayalso fit within a standard size shipping container 2200 for ease oftransport. One non-limiting example of a standard size shippingcontainer is a container having a length of about 40 feet, a height ofabout 8 to 9 feet and a width of about 8 feet.

FIG. 23 illustrates a flowchart of a method for servicing a rotor of awind turbine, according to an aspect of the present invention. Themethod 2300 includes a coupling step 2310 that couples at least onesupport cable (e.g., 302) to the blade root 24 or blade 22. The supportcable extends from the blade root 24 and into a hub 20 of the windturbine. A lowering step 2320 lowers the rotor blade 22 relative to thehub 20 using the support cable 302 such that the rotor blade 22 isspaced apart from the hub 20 by an initial vertical distance 146. Aninstalling step 2330 installs a rotor blade sling 1900 on the rotor 18.The rotor blade sling 1900 is configured to support the rotor blade 22that is in the 6 o'clock position. A coupling step 2340 couples therotor blade 22 to the rotor blade sling 1900. A lowering step 2350lowers the rotor blade 22 such that the rotor blade 22 is spaced apartfrom the hub by a distance slightly greater than the initial verticaldistance 146. A de-coupling step 2360 de-couples the support cables fromthe blade root 24 or rotor blade 22. An interposing step 2370 interposesa rotor servicing fixture 2000 between the rotor blade 22 (at the 6o'clock position) and the hub 20. The rotor servicing fixture 2000 isconfigured to transport a rotor part via a crane to or from the rotor 18or hub 20.

The method also permits the rotor servicing fixture 2000 to beinterposed between the hub 20 and rotor blade 22 without anyobstructions, and this enables large items, like the pitch bearing 150,to be removed and installed with the rotor blade still connected to therotor (e.g., via rotor blade sling 1900). This method could be used toconstruct new wind turbines or service, maintain or repair existing windturbines. Further, a low cost, low weight capacity crane, or an up-towerhoist or other equivalent device can be used to lower/raise the rotorservicing fixture 2000.

Referring now to FIGS. 24 and 25, a clamp assembly 400 that may beutilized as an alternative means for coupling one or more cables to therotor blade 22 for performing any of the various steps of the methodsdisclosed herein is illustrated in accordance with aspects of thepresent subject matter. Specifically, FIG. 24 illustrates a perspectiveview of the clamp assembly 400 installed around a portion of the bladeroot 24 of a rotor blade 22. Additionally, FIG. 25 illustrates a topview of the clamp assembly 400 and rotor blade 22 shown in FIG. 24.

In general, the clamp assembly 400 may include a plurality of curvedclamp members 402 configured to be engaged around the outercircumference of the rotor blade 22. Specifically, each clamp member 402may be configured to extend circumferentially around a portion of theblade root 24 of the rotor blade 22. In several embodiments, each clampmember 402 may be configured to be coupled to any adjacent clampmember(s) 402 via a pivotal connection. For example, as particularlyshown in FIG. 25, a hinge pin 404 may be configured to extend throughthe ends of each pair of adjacent clamp members 402, thereby allowingsuch clamp members to be pivoted or rotated relative to one another. Assuch, when the clamp assembly 400 is properly positioned along the bladeroot 24 at its desired installation location, the clamp members 402 maybe pivoted relative to one another to allow the clamp assembly 400 to betightened and/or engaged around the blade root 24.

It should be appreciated that, in general, the clamp members 402 may beconfigured to be actuated or otherwise rotated relative to one anotherusing any suitable actuating means known in the art. For example, inseveral embodiments, a suitable actuating cylinder 406 (e.g., anelectric cylinder or a fluid-driven cylinder) may be coupled betweeneach pair of adjacent clamp members 402 so that the cylinder 406 extendsacross the joint formed between the clamp members 402 via the hinge pin404. As particularly shown in FIG. 25, each actuating cylinder 406 mayinclude a piston cylinder 408 coupled to one of the adjacent clampmembers 402 and a piston rod 410 coupled to the other adjacent clampmember 402. As such, when the piston rod 410 is actuated relative topiston cylinder 408, the adjacent clamp members 402 may be rotatedrelative to one another, thereby allowing the clamp members 402 to beengaged around and/or disengaged from the rotor blade 22.

As shown in FIGS. 24 and 25, the clamp assembly 400 may also include oneor more coupling devices 412, such as mount rings, secured to one ormore of the clamp members 402 to allow a suitable cable(s) 414 to becoupled to the assembly 400. For instance, to initially install theclamp assembly 400 around the rotor blade 22, one or more cables 414 maybe coupled to the clamp assembly 400 to allow the assembly 400 to beproperly positioned vertically relative to the rotor blade 22, such asby coupling suitable lift cables to the clamp assembly 400 so that theassembly 400 may be lifted from the support surface 14 to a desiredinstallation location on the rotor blade 22.

In addition, when raising or lowering the rotor blade 22 relative to thehub 20, a suitable cable(s) 400 may be secured to one or more of theclamp members 402 to allow the rotor blade 22 to be up or down via suchcable(s). For instance, one or more support cables may be secured to theclamp assembly 400 to allow the rotor blade 22 to be initially loweredfrom the hub 20 by the initial vertical distance 146. Similarly, one ormore pulley cables may be coupled to the clamp assembly 400 to allow therotor blade 22 to be lowered or raised.

It should be appreciated that, in several embodiments, one or more clamppads 416 may be secured to one or more of the clamp members 402 suchthat the clamp pads 416 are positioned directly between the clampmember(s) 402 and the rotor blade 22 when the clamp assembly 400 isinstalled around the blade root 24. In one embodiment, the clamp pads416 may have a friction coating or surface that allows for improvedgripping of the rotor blade surface when the clamp members 402 areengaged around the blade root 24. Alternatively, the clamp pads 416 maybe formed from a foamed material or other suitable cushioning materialso as to provide a layer of protection for the outer surface of therotor blade 22.

The method and system of the present invention demonstratessubstantially improved results that were unexpected because the hub 20or rotor 18 can now be serviced without the use of an expensive cranethat is capable of lifting the entire rotor 18 or an entire blade 22.Hub, blade and rotor service is now more inexpensive and may be fasterdue to the fact that an expensive and limited availability crane doesnot have to be used. Further, maintenance and service costs are greatlyreduced and that makes wind energy more competitive economically withothers forms of power generation (e.g., fossil fuels, nuclear, solar,hydro, etc.).

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

The invention claimed is:
 1. A method to enable servicing of a rotor ofa wind turbine, the rotor having a rotatable hub with a plurality ofrotor blades mounted to the hub, the method comprising: positioning afirst rotor blade of the plurality of rotor blades of the rotor in a sixo'clock position; installing a rotor blade sling on the rotor by placingloops formed via at least one strap of the rotor blade sling overrespective rabbit-eared rotor blades of the plurality of rotor blades ata ten o'clock position and a two o'clock position, respectively, therotor blade sling further having one or more support straps secured tothe at least one strap that extend downward from the hub and one or morerigid bars extending from the hub and out away from the hub, the one ormore rigid bars coupled to the at least one strap and the one or moresupport straps, the one or more support straps supporting the firstrotor blade in a six o'clock position; and coupling the first rotorblade to the one or more support straps of the rotor blade sling.
 2. Themethod of claim 1, further comprising: lowering the first rotor blade,after the coupling step, such that the first rotor blade is spaced apartfrom the hub.
 3. The method of claim 1, wherein the at least one strapis comprised of a first strap and a second strap, and the one or morerigid bars are comprised of a first bar and a second bar.
 4. The methodof claim 3, wherein the first strap is coupled to the first bar and thesecond strap is coupled to the second bar.
 5. The method of claim 3,wherein the first strap is coupled to both the first bar and the secondbar, and the second strap is coupled to both the first bar and thesecond bar.
 6. The method of claim 3, further comprising a top strapcoupled to both the first strap and the second strap, the top strapextending along a top of the rotor blade in the ten o'clock position orthe two o'clock position.
 7. The method of claim 3, further comprising:installing a blade sock around an outer perimeter of the first rotorblade at an intermediate location defined between a blade root and ablade tip of the first rotor blade, wherein one or more tag lines areattached to the blade sock and extend to one or more support members. 8.A method for enabling servicing of a rotor of a wind turbine, the methodcomprising: positioning a rotor blade of the rotor in a six o'clockposition; installing a rotor blade sling on the rotor by positioning aloop formed via at least one strap of the rotor blade sling over atleast one rabbit-eared rotor blade in at least one of a ten o'clockposition or a two o'clock position, the rotor blade sling further havingone or more support straps secured to the at least one strap that extenddownward from the hub and one or more rigid bars extending from the huband out away from the hub, the one or more rigid bars coupled to the atleast one strap and the one or more support straps, the one or moresupport straps supporting the first rotor blade in a six o'clockposition; and coupling the rotor blade to the one or more support strapsof the rotor blade sling.
 9. The method of claim 8, wherein the at leastone strap is comprised of a first strap and a second strap, and the oneor more rigid bars are comprised of a first bar and a second bar. 10.The method of claim 9, wherein the first strap is coupled to the firstbar and the second strap is coupled to the second bar, or the firststrap is coupled to both the first bar and the second bar, and thesecond strap is coupled to both the first bar and the second bar.